Dottering auger catheter system

ABSTRACT

The Dottering Auger Catheter system is designed for penetration of tight stenoses or total occlusions (called blockages) as a precursor to balloon angioplasty, atherectomy, or any other vessel opening means that requires an initial passageway. Specifically, the Dottering Auger Catheter system consists of a centering catheter and a Dottering auger catheter which is a catheter that opens a passageway through an arterial blockage by passing its wedge shaped distal end through that blockage causing outward plastic deformation of the plaque; i.e., angioplasty. A centering catheter that surrounds the Dottering Auger Catheter can be used to center the distal end of the auger catheter just proximal to the blockage. The purpose of the auger type of Dottering catheter is to penetrate through the blockage by means of a self-tapping screw at the catheter&#39;s distal end. Once the first thread of the screw is pushed into the blockage, rotation of the catheter resulting from turning a handle at the catheter&#39;s proximal end will cause the screw to pull itself through the blockage while a push force on the handle is also applied. Once the auger has Dottered a passageway through the blockage, the auger catheter is removed and replaced with a guide wire. Once the guide wire is in place through the newly opened passageway, the centering catheter is removed and conventional balloon angioplasty or atherectomy can be performed to further enlarge the hole through the blockage thus restoring adequate blood flow.

This is a continuation-in-part application of Ser. No. 779,369, filedOct. 21, 1991, now U.S. Pat. No. 5,263,959 which issued on Nov. 23,1993.

FIELD OF USE

The Dottering Auger Catheter (DAC) system described herein is intendedto be used for penetration through a vessel blockage within a livingbody so as to make, a first passageway prior to balloon angioplasty oratherectomy.

BACKGROUND

Balloon angioplasty and atherectomy are well known modalities foropening vessels of a human body particularly arteries. However, if thereis an arterial blockage which cannot be penetrated by a guide wireand/or a balloon angioplasty or atherectomy catheter, surgical bypassvessel grafting is usually required to restore adequate blood flow tothat blocked artery. Although lasers have been used for making apassageway, (even through a total blockage) laser equipment is expensiveand laser treatment can result in removal of tissue from the arterialwall which could require surgical repair.

SUMMARY OF THE INVENTION

The present invention is a catheter system which makes possible thepenetration of tight stenoses or total occlusions (called blockages) asa precursor to balloon angioplasty, atherectomy, or any other vesselopening procedure that requires an initial passageway. Specifically, theDottering Auger Catheter (DAC) system consists of a centering catheterand a Dottering Auger Catheter (DAC). The DAC system may also include aguide wire placed through a central passageway of the DAC. Oneembodiment of the centering catheter employs a distally locatedinflatable balloon mounted on a catheter tube to center the distal endof the auger catheter just proximal to the blockage. The purpose of theauger catheter is to penetrate through the blockage by means of aself-tapping screw at the catheter's distal end. Once the first threadof the screw is pushed into the blockage, rotation of the catheter willcause the screw to pull itself through the blockage while a push forceon the DAC is also applied.

Once the DAC has Dottered a passageway through the blockage, it isremoved and replaced with a guide wire or a guide wire that was withinthe DAC is left in place through the blockage. With the guide wire inplace through the newly opened passageway, the centering catheter isremoved and conventional balloon angioplasty or atherectomy can beperformed to enlarge the passageway thus restoring adequate blood flow.

An advantage of the DAC system is that, if the auger inadvertentlypenetrates through the arterial wall, it can be withdrawn without theremoval of tissue from the vessel wall. Hence, the vessel wall wouldtypically seal itself without the requirement of surgical repair. If alaser were used to open a blockage, inadvertent passage of the beamthrough the arterial wall would result in wall tissue removal whichcould require surgical repair.

Other embodiments of the DAC system described herein include variousnon-balloon centering catheters and a needle-tipped penetrating catheterfor pushing through the blockage, and designs which include variousguide wires as part of the DAC system.

Furthermore, if a guide wire (without the DAC system) is used to try topenetrate through a blockage, it occasionally causes intimal dissection.The present invention by using a centering catheter and an auger screwis more likely to be able to penetrate through the blockage withoutcausing intimal dissection.

Thus it is an object of this system to provide a Dottering AugerCatheter (DAC) system consisting of a centering catheter and a DotteringAuger Catheter (DAC) which is capable of penetrating a tight stenosis ortotal occlusion (blockage) in an artery so that balloon angioplasty oratherectomy can be used subsequently for further dilation of thatblockage.

Another object of this invention is to provide a means for Dottering apassageway through a tight stenosis or total blockage with a device thatwill not cause damage even if the arterial wall is inadvertentlypenetrated.

Still another object of this invention is to utilize the DAC system tomake an opening through any tubular vessel in any living body.

Still another object of this invention is to utilize a DAC device withor without a centering catheter.

Still another object of this invention is to have a Dottering AugerCatheter system that includes a guide wire which passes through theentire Dottering Auger Catheter including the self-tapping screw at thecatheter's distal end.

Still another object of this invention is to utilize a centeringcatheter that tends to center the Dottering Auger Catheter within theartery's lumen or within an entry cone at the proximal side of thearterial blockage.

These and other objects and advantages of this invention will becomeapparent upon careful reading of the detailed description of thisinvention as presented herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a longitudinal cross section of the distal portion of theDottering Auger Catheter (DAC) system within an artery having a totalblockage.

FIG. 1B is a longitudinal cross section of a penetration catheter to beused within a centering catheter.

FIG. 2 is a transverse cross section of the DAC system at position 2--2of FIG. 1A.

FIG. 3 is a longitudinal cross section at the DAC system's proximal endshowing a handle for applying push and torque to the auger catheter.

FIG. 4 is a longitudinal cross section of another embodiment of the DACsystem showing a centering catheter with a uniform outer diameter.

FIG. 5 is a longitudinal cross section of another centering catheterhaving a spherical protrusion near its distal end.

FIG. 6 is a longitudinal cross section of another centering catheterhaving a plurality of expandable spokes near the catheter's distal end.

FIG. 7 is a longitudinal cross section of a centering catheter having asteel, flat-wire, helical coil interior structure.

FIG. 8 is a longitudinal cross section of the distal portion of analternative embodiment of the Dottering Auger Catheter (DAC) systemwithin an artery having a total blockage.

FIG. 9 is a cross section of a different embodiment of the DAC without acentering catheter and with a specially shaped guide wire.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1A is a longitudinal cross section showing a distal portion of theDAC system 10 within an artery which has a total occlusion (blockage).The DAC system 10 consists of the Dottering Auger Catheter (DAC) 20 anda centering catheter 40. The DAC 20 consists of a proximal steel tube22, a flexible catheter section 24 and a distal, self-tapping screw 30.The proximal end of the tube 22 extends outside of the patient's body(see FIG. 3) where a conventional handle can be mounted whichfacilitates the operator's ability to simultaneously apply a rotationaltorque (twist) and a push force to the DAC 20. The tube 22 is joined atits distal end to the flexible catheter section 24 which is joined atits distal end to the auger screw 30. Thus, the push and twist impartedat the proximal end of the tube 22 will be imparted to the screw 30 sothat it will screw itself into the arterial blockage.

The self-tapping screw 30 consists of a shoulder 32 which is joined(typically by an adhesive or by brazing, soldering or welding) to thecatheter section 24. Further the screw 30 has a conical section 34 whichmakes a progressively larger central opening in the plaque of theblockage as the screw 30 is advanced by rotating it and pushing itforward through the blockage. The process of enlarging a hole through ablockage by pushing forward a tapered or conically shaped nose of acatheter is called "Dottering". This Dottering process is accomplishedby plastic deformation of the blockage tissue by the self-tapping screw30 and the distal end of the flexible section 24 without any significanttissue removal. As seen in FIG. 1A, it is important that there is asmooth transition of the outer surface of the conical section 34 ontothe outer surface of the distal end of the flexible section 24 so thatthe screw threads can readily pull through the blockage tissue withoutexcessive torque applied to the auger catheter 20.

The screw 30 also has an extremely sharp point 36 at its distal end toassist in pushing through the plaque. The screw 30 would typically be0.5 to 2 cm. long and 0.2 to 2.0 mm in diameter.

The flexible section 24 of the auger 20 could be fabricated from aplastic such as nylon, polyethylene, polyurethane, etc. or it could befabricated from braided metal material or made from a flat metal wirecoil as is well known in the art of torque cables. The length of theflexible section 24 would typically be between 5 and 50 cm, and theoutside diameter would typically be between 0.2 and 2.0 mm with a wallthickness between 0.01 and 0.05 min.

The steel tube 22 would typically have a wall thickness between 0.05 and0.30 mm and would be fashioned from a material such as type 304stainless steel. The same stain-less could be used for all other metalparts of the DAC system 10 such as the screw 30.

The centering catheter 40 consists of a plastic tube 42 having a centrallumen (or passageway) 43 through which the DAC 20 can be passed, and asecond lumen 44 through which a fluid such as air or contrast medium canbe passed in order to inflate the balloon 46 that is located near thedistal end of the centering catheter 40. Such a fluid will fill thechamber 48 that lies internal to the balloon 46 thus centering thedistal ends of the tube 42 and the central lumen 43 within the artery.Thus, the distal end of the DAC 20 which lies within the lumen 43 willalso tend to be centered so that the point 36 will be centered onto theproximal surface of the blockage. Thus the DAC 20 can be pushed throughnear the blockage's center which reduces the possibility that the screw30 will penetrate through the arterial wall. Even if it does penetratethrough an arterial wall, the screw 30 could be screwed back withoutresulting in serious harm to the patient. This is because no piece ofarterial wall would actually be removed by the screw 30 as would be thecase if a laser beam or cutting blade actually removed a piece of thearterial wall. An inadvertent penetration of the arterial wall with thedistal end of the DAC 20 would tend to be self-sealing.

FIG. 1B shows an alternative embodiment of the DAC 20. Specifically, thepenetration catheter 21 shown in FIG. 1B would pass through the centralpassageway of a centering catheter and could penetrate through ablockage by pushing or with the assistance of ultrasonic vibrationapplied at its distal end. Like the DAC 20, the penetration catheter 21would not remove tissue and would be centered by the centering catheteras it passes through the blockage which reduces the possibility ofintimal dissection and/or arterial wall perforation.

FIG. 2 shows a cross section of the DAC system 10 at position 2--2 ofFIG. 1A. At the center is the auger tube 22 which can slide within thecentral lumen 43 of the catheter tube 42. The lumen 44 forms apassageway for fluid to inflate or deflate the balloon 46.

FIG. 3 illustrates the proximal end of the DAC system 10 which liesoutside of the patient's body. The proximal end of the tube 42 wouldterminate in a Tuohy-Borst gland or hemostasis valve 47 formed as a softelastomer seal. This valve 47 seals against the outer surface of thesteel tube 22. A side arm 45 near the proximal end of the tube 42 has alumen 49 which is in fluid communication with the balloon lumen 44. Thusinflation and deflation of the balloon 46 (of FIG. 1A) can beaccomplished by injecting fluid through the lumen 49 of the side port45. The design of the valve 47 and side arm 49 would be typical of valveand side port designs used at the proximal end of the introducer sheathswhich are well known in this art. Another side arm (not shown) could beused to deliver contrast medium to the distal end of the lumen 43.

A steel or plastic handle 23 formed as shown in FIG. 3 would be joinedby spot welding through the proximal end of the tube 22 onto theextension 25 of the handle 23. Other handle designs could beaccomplished by plastic molding or adhesive bonding onto the proximalend of the tube 22.

The total lengths of the centering catheter 40 and the DAC 20 can bepredetermined so that the length "L" shown in FIG. 3 is an exactly knownlength when the point 36 is co-extensive with the distal end of thecentering catheter 40. For example, with the geometry of the distal endof the DAC system 10 as shown in FIG. 1A, when the point 36 extends (letus say) 1.0 mm beyond the distal end of the centering catheter 40, thenthe dimension "L" might be 2.0 cm. Thus the most that the screw 30 couldbe advanced through a blockage would be 3.0 cm. Further, the outersurface of the tube 22 within the length "L" shown in FIG. 3 could havemarks which indicate to the doctor how far the point 36 has advancedbeyond the centering catheter's distal end.

The procedure for using the DAC system 10 based on the embodiment ofFIGS. 1A, 2 and 3 would be as follows:

(1) Angiography would be used to indicate an arterial blockage.

(2) A 1.0 mm diameter guide wire would then be advanced through anintroducer sheath at the patient's groin (and possibly through a guidingcatheter) until the guide wire's distal end touches the proximal surfaceof the blockage.

(3) The centering catheter would then be advanced over the guide wireuntil its distal end is in contact with the blockage's proximal surface.

(4) The guide wire would then be removed and the balloon would beinflated to a moderate pressure such as 0.3 atmospheres.

(5) Contrast medium would then be injected through the central lumen ofthe centering catheter to verify its position in the artery. The lengthof the blockage would be noted.

(6) A DAC having a diameter of 1.0 mm would then be advanced through thecentering catheter until its distal end was in contact with theblockage.

(7) Using the scale at the proximal end of the tube 22, the auger screwwould be advanced a distance somewhat greater that the length of theblockage by turning the auger's handle in a known direction such asclockwise while pushing it forward.

(8) The auger would then be removed and contrast medium would beinjected through the central lumen of the centering catheter to verifythat the DAC had Dottered a passageway through the blockage.

(9) A guide wire for an angioplasty balloon catheter (typically 0.35 mmdiameter) would then be advanced through the centering catheter andthrough the newly formed passageway in the blockage.

(10) The centering catheter would then be removed and a balloonangioplasty or atherectomy procedure would be performed.

FIG. 4 shows an alternative embodiment of a centering catheter 50 havinga uniform outer diameter which can be used to adequately center an augercatheter 60 inside a comparatively small artery. The centering catheter50 is considerably simpler and therefore less costly and complex inoperation as compared to the balloon centering catheter 40 of FIG. 1A.If, for example, the internal diameter of the artery is 2.0 mm, then acentering catheter 50 could have an outside diameter of 1.9 mm, a wallthickness of 0.4 mm, and the auger catheter 60 could have an outerdiameter of 1.0 mm (0.039 inches) which could readily slide within thatcentering catheter.

FIG. 5 shows another design of a centering catheter 70 which employs aspherically shaped bulge 72 near the catheter's distal end. Thiscatheter 70 could have the same dimensions as the catheter 50, exceptthe outer diameter "D" of the bulge 72 would lie between 2.0 and 6.0 mm.When pushed through a guiding catheter or introducer sheath, the bulge72 could collapse to slide within the inside cylindrical surface of thatguiding catheter or sheath. Once in an artery, the bulge would expand toaccurately center the distal end 74 of the centering catheter 70 in anartery just proximal to a blockage. The distal end 74 could be maderadiopaque so that it could be visualized with fluoroscopy. FIG. 6illustrates still another embodiment of a centering catheter 80 whichhas a plurality of spokes 84 near its distal end which connect to adistal ring 86. In its normal position, the spokes 86 of this 4 spokedesign (3 spokes are shown in this longitudinal cross section) bulge outslightly. However, when the distal ring 84 is pushed against a blockage,the spokes 86 will bulge in an outward direction as shown by the dottedlines 84' in FIG. 6, and the distal ring 86 will move in a proximaldirection to a position as indicated by the dotted lines 86'.

FIG. 7 shows another centering catheter 88 in which the interiorstructure is a helical, flat-wire steel coil 89. One purpose of the coil89 is to prevent the auger screw threads from catching on the interiorplastic surface of the centering catheter 88. Such a metal helical coil89 would be covered on its outer (and possible inner) surface by aplastic tube 87 so that the centering catheter would slide smoothlywithin an artery. Another purpose of the coil 89 is to make the distalend of the centering catheter steerable so that the distal tip of theauger could be aimed at some angle relative to the blockage to avoidpenetrating the wall in a curved artery. Composite materials catheterdesigns of this type are described in detail in U.S. Pat. No. 5,180,376entitled "A Non-Buckling Thin-Walled Sheath for Percutaneous Insertionof Transluminal Catheters"; which issued on Jan. 19, 1993 to Robert E.Fischell; which patent is included herein by reference.

Another embodiment of the present invention is shown in FIG. 8. In thisembodiment, the DAC systems 90 includes a centering catheter 91, aDottering Auger Catheter (DAC) 94 and a guide wire 98. The centeringcatheter 91 has an elongated, plastic body 92 and a radiopaque marker:ring 93 at or near its distal end. The design of the distal region ofthe centering catheter 91 could be similar to any of the centeringcatheters previously described herein. The DAC 94 consists of a flexiblesection 95 whose distal end is joined to the proximal end of aself-tapping auger screw 96. The outer surface at the proximal end ofthe screw 96 is continuous with the distal end of the flexible section95, thus forming an ideal shape for Dottering through an arterialblockage. The outer surface of a distal portion of the DAC 94 mayadvantageously be coated with a lubricious coating to decrease thestress put on the blockage tissue during rotation of the screw 96 as theDAC 94 is advanced through the blockage tissue. The ring 93 and thescrew 96 are ideally made from a highly opaque, dense metal such astantalum or an alloy of platinum, or gold. Such objects appear to bevery bright in fluoroscopy, thereby helping the interventionalcardiologist to locate the tips of the centering catheter 91 and DAC 94relative to the arterial blockage.

The DAC system 90 also includes a guide wire 98 that can be movedslideably through a passageway that lies at the center of the DAC 94;which passageway includes a hole through the center of the screw 96.Typically a 0.35 mm plus or minus 0.10 mm diameter guide wire would beused, and the hole in the screw would typically be made 0.02 to 0.05 mmlarger in diameter as compared to the guide wire 98. The proximal end ofthe DAC system 90 would be of a similar design to that shown in FIG. 3except that the guide wire 98 would extend through a seal such as ahemostasis valve in the DAC's proximal handle. By using a guide wire 98to center the DAC 94, it is possible to eliminate the need for thecentering catheter 91.

As shown in FIG. 8, many occlusions have a funnel like entry cone whichcan lead into what might be the remains of a true lumen of the blockage.This true lumen may actually exist, or it could be the last tissue thatstenosed making it somewhat softer than the older parts of the blockage.The design shown in FIG. 8 is ideally suited for placing the screw 96through this true lumen. This guide wire design of the DAC system isdesirable to reduce the possibility of intimal dissection of the plaqueaway from the arterial wall. A lubricious coating at the distal end ofthe DAC 94 also decreases the possibility of intimal dissection. Aprocedure using the DAC system 90 for Dottering through a blockageshould be as follows:

(1) The guide wire 98 is advanced through the arterial system but cannotpenetrate through a blockage.

(2) The centering catheter 91 and the DAC 94 are advanced together overthe guide wire 98 until fluoroscopy reveals that their distal ends arecontacting the blockage's proximal surface.

(3) A handle at the proximal end of the DAC 94 is pushed forward whilebeing rotated to advance screw 96, and a distal section of the flexiblesection 95 through the blockage.

(4) The guide wire 98 is advanced through the blockage as the screw 96moves forward or it can be advanced after a Dottered passageway has beenformed in the blockage.

(5) The centering catheter 91 and the DAC 94 are then removed out of thebody and a balloon angioplasty or atherectomy catheter is then advancedover the guide wire 98 to further open the arterial lumen with theblockage.

It should be understood that it might be possible to place a guide wireacross the true lumen of the blockage, but not possible to advance aballoon angioplasty or atherectomy catheter through the remaining verytight stenosis. In such a case, the balloon angioplasty or atherectomycatheter would be pulled out with the guide wire being left in placeacross the blockage. The DAC 94 could then be advanced over the guidewire and used to enlarge the diameter of the true lumen. In this case,the centering catheter 91 might or might not be used. The DAC 94 canDotter a sufficiently large diameter in the lumen of the stenosis toallow for the passage of a balloon angioplasty or atherectomy catheter.

FIG. 9 shows a special guide wire 99 having a very sharp point at itsdistal end and a shoulder 100 that engages the distal tip of the screw101. This design would operate by having both the guide wire 99 and thescrew 101 advanced together through the blockage. The design of FIG. 9would preclude the possibility that blockage tissue would be caught inthe hole of the screw 101 as it Dotters through the blockage.

Although the discussion herein was concerned with opening an arterialblockage, this technique could also be applied to opening otherblockages of vessels in living bodies such as bile ducts, fallopian orbronchial tubes, urethras, etc. through which it is desired to make apassageway. Furthermore, the centering and balloon dilation functionscould both be accomplished with the same balloon angioplasty catheter.Still further, the auger device could be used without a centeringcatheter (for example as shown in FIG. 9) and it would still function toopen an occluded blood vessel or duct.

Various other modifications, adaptations, and alternative designs are ofcourse possible in light of the above teachings. Therefore, it should beunderstood at this time that within the scope of the appended claims,the invention may be practiced otherwise than as specifically describedherein.

What is claimed is:
 1. A catheter system for forming a passagewaythrough a blockage in a human artery comprising:a centering catheter inthe form of an elongated cylinder having proximal and distal ends, thecentering catheter being adapted to be percutaneously inserted into anartery and then advanced until its distal end contacts the proximalsurface of an arterial blockage; an auger catheter having proximal anddistal ends and having a self-tapping screw formed from a radiopaquemetal at its distal end and also having a flexible section whose distalend is joined to the screw's proximal end, the auger catheter beingadapted to be advanced within the centering catheter until a sharp pointat the screw's distal end contacts the proximal surface of the blockage,the outer surface of the screw having a smooth transition from thescrew's proximal end onto the flexible section's distal end, the augercatheter also having a handle at its proximal end that lies outside thepatient's body, the handle and screw cooperating so that when the handleis pushed forward and rotated in a particular direction, the screw willadvance in a forward direction thereby forming a passageway though theblockage by plastically deforming the blockage tissue without anysignificant tissue removal.
 2. The catheter system of claim 1 whereinthe centering catheter is of a uniform outer diameter throughout itslength that lies within the patient's arterial system.
 3. The cathetersystem of claim 1 wherein the centering catheter has a bulge near itsdistal end to facilitate centering of the centering catheter's distalend.
 4. The catheter system of claim 3 wherein the bulge collapsesinward when pushed within a guiding catheter or sheath and then expandsoutward after the distal end of the centering catheter extends beyondthe guiding catheter or sheath.
 5. The catheter system of claim 1wherein a distal portion of the centering catheter has a plurality ofspokes which are flexibly attached to a distal end ring, the spokesbeing adapted to bulge outwardly when the centering catheter is pushedin a forward direction after the distal ring has engaged the proximalsurface of the blockage.
 6. The catheter system of claim 1 wherein thecentering catheter has a first and central lumen which forms apassageway for the auger, and a second lumen which is fluidily isolatedfrom the first lumen, the second lumen allowing fluid communicationbetween the centering catheter's proximal end and an inflatable balloonlocated near the centering catheter's distal end, the inflatable balloonbeing adapted to center the centering catheter's distal end when theballoon is inflated.
 7. The catheter system of claim 1 wherein thecentering catheter has a flat wire helical coil on at least part of itsinterior.
 8. The catheter system of claim 1 wherein the centeringcatheter has a fluid tight seal at its proximal end which makes a fluidseal against the outer cylindrical surface of the auger catheter.
 9. Thecatheter system of claim 1 wherein the distance that the distal end ofthe screw extends beyond the distal end of the centering catheter isindicated by marks on the outer surface of the auger catheter's proximalend.
 10. The catheter system of claim 1 wherein the centering catheterhas a radiopaque marker at or near its distal end.
 11. The cathetersystem of claim 1 wherein at least a distal portion of the augercatheter has a lubricious coating.
 12. The catheter system of claim 1wherein a radiopaque marker is located on a distal portion of thecentering catheter.
 13. The catheter system of claim 1 wherein the augercatheter has a central passageway throughout its entire length.
 14. Thecatheter system of claim 13 further comprising a guide wire that isadapted to move slideably through the central passageway of the augercatheter.
 15. The catheter system of claim 13 further comprising a guidewire having a sharp point at its distal end to assist in the Dotteringin process.
 16. The catheter system of claim 15 wherein the guide wireis adapted to be pushed forward by the auger catheter's screw as thescrew is advanced through the blockage tissue.
 17. A catheter system forforming a passageway through a blockage in a human artery comprising:anauger catheter having proximal and distal ends and having a centralpassageway throughout its entire length and also having a self-tappingscrew at its distal end and also having a flexible section whose distalend is joined to the screw's proximal end, the auger catheter beingadapted to be advanced within an artery of a human body until a sharppoint at the screw's distal end contacts the proximal surface of theblockage, the outer surface of the screw having a smooth transition fromthe screw's proximal end onto the flexible section's distal end, theauger catheter also having a handle at its proximal end that liesoutside the patient's body, the handle and screw cooperating so thatwhen the handle is pushed forward and rotated in a particular direction,the screw will advance in a forward direction thereby forming apassageway though the blockage by plastically deforming the blockagetissue without any significant tissue removal; and, a guide wire that isadapted to move slideably through the central passageway of the augercatheter.
 18. The catheter system of claim 17 wherein at least a distalportion of the auger catheter has a lubricious coating.
 19. The cathetersystem of claim 17 wherein at least part of the self-tapping screw atthe auger catheter's distal end is formed from a radiopaque metal.